Australian Shield

The word shield is used because it refers to ancient, molten rock which has cooled and solidified.

[1] The Australian Shield has a characteristic depth of 4.5 kilometres (2.8 mi) and an estimated age of 2.8 to 3.5 billion years.

[2][3] In places younger sedimentary rock covers the shield's Precambrian surface.

[4] It occupies the portion of Australia west of a line running north–south roughly from the eastern shore of Arnhem Land on the Bay or Gulf of Carpentaria to the Eyre Peninsula in the state of South Australia, and skirting to the west of the Simpson Desert in the interior.

Erosion and weathering have created striking, isolated rock formations called mesas or buttes in many parts of the shield, including the Kimberleys and Pilbara districts of Western Australia and Arnhem Land in the Northern Territory.